Flicker as a tool for characterizing planets though asterodensity profiling

TY - JOUR

T1 - Flicker as a tool for characterizing planets though asterodensity profiling

AU - Kipping, D. M.

AU - Bastien, F. A.

AU - Stassun, K. G.

AU - Chaplin, W. J.

AU - Huber, D.

AU - Buchhave, Lars A.

PY - 2014/4/20

Y1 - 2014/4/20

N2 - Variability in the time series brightness of a star on a timescale of 8 hr, known as "flicker," has been previously demonstrated to serve as a proxy for the surface gravity of a star by Bastien et al. Although surface gravity is crucial for stellar classification, it is the mean stellar density that is most useful when studying transiting exoplanets, due to its direct impact on the transit light curve shape. Indeed, an accurate and independent measure of the stellar density can be leveraged to infer subtle properties of a transiting system, such as the companion's orbital eccentricity via asterodensity profiling (AP). We here calibrate flicker to the mean stellar density of 439 Kepler targets with asteroseismology, allowing us to derive a new empirical relation given by log10 (ρ (kg m-3)) = 5.413-1.850log10 (F 8 (ppm)). The calibration is valid for stars with 4500 < T eff < 6500 K, K P < 14, and flicker estimates corresponding to stars with 3.25 < log g < 4.43. Our relation has a model error in the stellar density of 31.7% and so has 8 times lower precision than that from asteroseismology but is applicable to a sample 40 times greater. Flicker therefore provides an empirical method to enable AP on hundreds of planetary candidates from present and future missions.

AB - Variability in the time series brightness of a star on a timescale of 8 hr, known as "flicker," has been previously demonstrated to serve as a proxy for the surface gravity of a star by Bastien et al. Although surface gravity is crucial for stellar classification, it is the mean stellar density that is most useful when studying transiting exoplanets, due to its direct impact on the transit light curve shape. Indeed, an accurate and independent measure of the stellar density can be leveraged to infer subtle properties of a transiting system, such as the companion's orbital eccentricity via asterodensity profiling (AP). We here calibrate flicker to the mean stellar density of 439 Kepler targets with asteroseismology, allowing us to derive a new empirical relation given by log10 (ρ (kg m-3)) = 5.413-1.850log10 (F 8 (ppm)). The calibration is valid for stars with 4500 < T eff < 6500 K, K P < 14, and flicker estimates corresponding to stars with 3.25 < log g < 4.43. Our relation has a model error in the stellar density of 31.7% and so has 8 times lower precision than that from asteroseismology but is applicable to a sample 40 times greater. Flicker therefore provides an empirical method to enable AP on hundreds of planetary candidates from present and future missions.

U2 - 10.1088/2041-8205/785/2/L32

DO - 10.1088/2041-8205/785/2/L32

M3 - Journal article

SN - 2041-8205

VL - 785

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

IS - 2

M1 - L32

ER -